I live on the main unit. 

Tell the tenant if they are having problems affording rent, they are welcome to give notice and find a less expensive place to live.

(For context, it's a 2700 sf 4 bd 3 bath house in an upscale Northern California suburb.)Kitchen A: Traditional, features a 48 in fridge, 36 in cooktop, window sink (no view), pantry.Kitchen B: Designer, features a 60 in fridge, 48 in range, large kitchen window (no view), sink facing living/dining room; unfortunately no pantryKitchen C: A Little Bit of Both, features a 48 in fridge, 48 in range, sink facing living/dining room, pantry, unfortunately there's no window.Total countertop space is roughly the same (22 ft)  in all three layouts.

I'm more interested in purchasing 10 homes to have fully paid off by the time I retire, as I'm not living on the cash flow w/ current job. 

I currently live in the Bay Area, but I’ve decided to start investing in the Jackson County/MO area.

I doubt it was actually live.

Your primary residence - if you've lived in it for 2 out of the 5 years prior to selling you'll get the $250K/$500K tax free iike @Clint Galliano said. 

You can gauge this risk by checking state average homeowners insurance rates.Few people live in cities that meet all the above requirements.

. --- They will offer to fix them in exchange for lower rent, but ask yourself, if the tenant has been living there for 25 years, why isn't everything fixed already?

For scaling your portfolio, consider house hacking another multi-family property to minimize living expenses while building equity.